Weapon, Very Rare
If a natural 20 is rolled on the attack roll, this weapon cuts off the target's head. If the creature cannot survive without a head, it instantly dies. If a creature is immune to slashing damage, or has a legendary resistance, they are not instantly killed. If this attack is not fatal to the target, it instead takes an additional 6d8 slashing damage.
Made with a base of Ebony, it also has the non-magical effects of an Ebony weapon.